Regenerated cellulose pellicle



Patented Nov. 14, 1939 STATES PATENT OFFICE REGENERATED CELLULOSE PELLICLE No Drawing. Application December 22, 1936,

Serial No. 117,183

1 Claim.

This invention relates to the prevention of iron stains, and in particular, it pertains to the treatment of pellicles of non-fibrous character, such as those made from regenerated cellulose, which are adapted for use as bottle caps, bands and the like, in order to prevent staining of the pellicles when dried in contact with iron or metals containing iron as a component.

This is a continuation-in-part application of my copending application Serial No. 737,428, filed July 28, 1934.

Heretofore, when regenerated cellulose caps and bands in a gel condition, i. e., after coagulation and regeneration but before being dried, were applied to bottles having iron-containing metallic caps or appurtenances, a common defect has been that the cellulcse caps and bands developed rust stains which appeared on the surface and greatly injured the appearance of the finished package. In addition, the portion stained with rust became weakened and tended to crack.

Caps and bands of regenerated cellulose, which have been manufactured, for instance, by the viscose process, are customarily stored and shipped to consumers in an aqueous solution containing glycerin or other softener. The consumer withdraws the cap or band from the shipping solution and applies it over the bottle or other desired container or object and allows it to dry. In dryin it shrinks considerably and grips the object tightly. If, in so doing, the cap or band comes into contact with iron or metal containing iron, rust stains will develop, which impart an unsightly appearance and a destructive action to the cap or band. When the cap or band is opaque, as for example when it contains titanium oxide or other light colored pigment as an opaquing agent, the unsightliness due to the iron stain is quite pronounced.

It is an object of this invention to produce non-fibrous pellicles which resist staining when in contact with iron-containing metals. It is a further object of this invention to prevent iron stains in caps and bands of non-fibrous sheet materials which are applied in a gel state to bottles or other containers having iron-containing metal caps or appurtenances, and which caps and bands attain their ultimate condition as the result of shrinkage through the loss of moisture. Other objects of the invention will appear hereinafter.

The objects of this invention are accomplished, in the preferred form, by shipping the covering material in an aqueous solution containing a small amount of a stain-preventative material of the type herein described.

I have discovered that iron stains can be greatly diminished and even completely prevented by using gel cellulosic pellicles which have been treated with a solution of a compound which inhibits the formation and/or absorption of soluble iron compounds. In applying the principles of the invention, the gel pellicles are immersed in an aqueous solution of the stain-preventing compound and the immersion is continued until equilibrium is established between the solution and the pellicles. It is customary to ship gel regenerated cellulose bottle caps and bands in a dilute aqueous glycerin solution, the glycerin acting as a softener. The caps may be placed in the shipping container and the treating solution containing the desired amount of glycerin and staininhibitor, then poured in until it covers the pelliclesyafter which the container may be closed and shipped, and the treated caps, whenever desired, placed on the bottles or like vessels, and; permitted to dry and shrink over the tops of the bottles. I

The present invention relates to the use of water-soluble amines, for example, alkanol amines such as triethanol amine, tripropanol amine and tributanol amine for preventing or reducing the iron-staining of pellicles.

The compounds used in accordance with the present invention need only to be soluble in water to the extent desired to inhibit iron-staining, e. g., so as to form a concentration ordinarily not less than about one-half per cent. Compounds which would otherwise be suitable but which have. a too high or a too low pH, when dissolved in aqueous solution, may sometimes be used by adding buffer materials so that the final pH may be regulated within the desired limits, for example, to obtain a final pH corresponding to that of an aqueous solution of triethanol amine.

The following illustrative example describes a mode of applying the invention:

Example I .Gel caps and/or bands of regenerated cellulose prepared from viscose and adapted to be applied to bottle tops and necks are packed in a shipping container containing glycerin and triethanol amine, in such a concentration that, after equilibrium with the moisture in the caps is reached, the shipping solution contains about 5% of glycerin and about 0.2% of triethanol amine.

Caps and bands treated in accordance with the preceding example, when dried down over iron or iron-containing metal bottle caps, even when the latter are filed down to expose the bare metal, remain completely free from rust stains even after a long period of time.

The proportion of anti-staining compounds present in the equilibrium solution which is used to ship the pellicles may vary from a fraction of a percent up to the limit of solubility of the compound in the solution. For most practical purposes, the equilibrium solution will contain from one-tenth per cent to five per cent of said compound.

The invention, in its preferred form, applies to the treatment of regenerated cellulose pellicles While the invention is preferably applied to gel pellicles, it will be understood that the scope of the invention includes the treatment of pellicles which have been dried and then rewetted prior to treatment.

Moreover, it is to be understood that instead of shipping pellicles submerged in a shipping solution, they may, of course, be removed from a shipping solution which has attained equilibrium and shipped in a moist condition to the point of use.

Any variation or modification which conforms to the spirit of the invention is intended to be included within the scope of the claim.

I claim:

A softened, wet, regenerated cellulosic pellicle which is subject'to shrinking by loss of water, and which is subject to staining when shrunk in contact with iron, containing suflicient alkanol amine from the group consisting of triethanol amine, tripropanol amine and tributanol amine to prevent rusting of iron when the pellicle is dried in contact therewith.

THOMAS F. BANIGAN. 

